A small group of Catholics led by an ailing priest believe Satan intends to become man in the same way that God did in the person of Jesus. The writings of a possessed mental patient lead them to Peter Kelson, a serial killer researcher. They believe Satan will occupy his body. Maya Larkin, the group's youngest member, goes to Peter to investigate further and persuade him of the possibility of Evil incarnate. Other signs appear to him as he and Maya embark on a journey filled with strange occurrences, self-discovery, and an epic showdown.